(a) Scientific excellence: Limited energy resources and pressures of global warming require industry to reduce its net-energy or "carbon footprint". Given that >60% of energy in manufacturing is wasted as heat has triggered interest in thermal-energy scavenging for temperatures <1000K and worldwide development of thermophotovoltaic (TPV) devices. As early as 2008, Technology Strategy Board (TSB) and EPSRC invested ~£3M creating TPV R&D consortium (Lancaster) with UK first demonstration of InAs TPVs reported in 2015 (co-author, Kesaria). However, the InAs and subsequent InSb-based devices suffer from severe temperature instabilities and require subsequent cooling rendering these devices net-energy-consuming. Recently, a new compound semiconductor, InN, has been theoretically predicted (2017, MIT) with both thermally-stable crystal structure and spectral response promising robust, un-cooled performance. To date, no diode demonstration has been reported creating a scenario for rich academic exploration/development for PhD study. In support of this studentship, Dr. Kesaria and co-supervisor Prof. Min Gao, are well-placed to explore this opportunity utilising III-N molecular beam epitaxy (MBE), ICS fabrication and Cardiff device and materials characterization facilities.

Project aims, methods, outcomes: The studentship aims to demonstrate temperature-stable TPVs with blackbody response ~1000K. The student will develop new methods to grow InN material using MBE then characterise its structure, optical properties by XRD, PL and FTIR in Ser-Cymru laboratory. Following device simulation (Sentaurus, Gao) and doping studies, a p-i-n structure is grown, fabricated into mesa diodes and characterised. Special flash-test I-Vs will check short-circuit and open-voltage enhancement in Prof Gao's lab.

Scientific challenges: Breakthrough opportunities include doping studies (InN is intrinsically n-type), diode passivation (surface accumulation at etched-sidewalls) and InN thermally-stable TPV demonstration (first to date).

(b)Feasibility of completion within 3.5years: The project has four stages (yr0.0-0.5)literature search, MBE, cleanroom, Sentaurus training (yr0.5-1.5)InN on Si epitaxy, doping studies, TPV modelling (yr1.5-2.5)device development; (yr2.5-3.5)device demonstrations, reporting, viva.